1. Technical Field
The present disclosure relates to gauges that indicate the state or condition of a bone fixation device, e.g., whether the bone fixation device is locked or unlocked. More particularly the present disclosure relates to a lock indicator gauge to indicate whether a bone screw, e.g., a multiplanar taper lock screw for securing a spinal rod to a vertebra, is in a locked or in an unlocked state.
2. Background of Related Art
Correction of a spinal deformity typically requires stabilization and fixation of vertebrae in a particular spatial relationship. Surgical spinal correction procedures involve the placement of a plurality of bone pins, anchors, cables, hooks, or screws placed in adjacent vertebrae and using spinal rods to maintain a predetermined spatial relationship between the vertebrae.
These devices commonly employ longitudinal link rods secured to vertebrae by spinal bone fixation fasteners, such as pedicle screws and hooks. Conventional devices for locking a spinal rod to a fixation hook or screw do not offer the needed variability to allow the spinal rod to be easily connected to adjacent vertebrae that are not aligned on the same plane.
In some cases, such devices are permanently implanted in the subject. However, in other cases, the devices may be subsequently removed when no longer needed. Moreover, it is common that devices that were intended to be permanently implanted may require subsequent procedures or revisions as the patient's condition necessitates. For this reason, it is desirable that an implanted device be readily locked and unlocked as desired by a surgeon. Determination of whether an implanted device is locked or unlocked may not be readily apparent by merely visually inspecting the device.